Start typing a task name in the What? column and
the auto completion will suggest a list of dictionary entries that are related to the text you entered:

The auto completion functionality suggests dictionary entries.

Choose the dictionary entry you want to link to the task by clicking it
or selecting it with the arrow keys and pressing Enter. The task will be will be linked to the dictionary entry. You can now edit the name of the task, the dictionary entry will stay linked to it.

Linked information will get a small dictionary icon:

The task ‘Create Order template’ is connected to a dictionary entry.

You can also connect single attribute values to dictionary
entries. Whenever you add textual information to an attribute the auto
completion will suggest dictionary entries in the same way: